AU769692B2 - Apparatus and method for welding pipes together - Google Patents

Apparatus and method for welding pipes together Download PDF

Info

Publication number
AU769692B2
AU769692B2 AU22872/00A AU2287200A AU769692B2 AU 769692 B2 AU769692 B2 AU 769692B2 AU 22872/00 A AU22872/00 A AU 22872/00A AU 2287200 A AU2287200 A AU 2287200A AU 769692 B2 AU769692 B2 AU 769692B2
Authority
AU
Australia
Prior art keywords
welding
pipes
torches
groove
torch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
AU22872/00A
Other versions
AU2287200A (en
Inventor
Antonio Belloni
Renato Bonasorte
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saipem SpA
Original Assignee
Saipem SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
Priority to GB9828727 priority Critical
Priority to GBGB9828727.9A priority patent/GB9828727D0/en
Application filed by Saipem SpA filed Critical Saipem SpA
Priority to PCT/EP1999/010505 priority patent/WO2000038872A1/en
Publication of AU2287200A publication Critical patent/AU2287200A/en
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=10845093&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=AU769692(B2) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Publication of AU769692B2 publication Critical patent/AU769692B2/en
Application granted granted Critical
Anticipated expiration legal-status Critical
Expired legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00Arc welding or cutting
    • B23K9/12Automatic feeding or moving of electrodes or work for spot or seam welding or cutting
    • B23K9/127Means for tracking lines during arc welding or cutting
    • B23K9/1272Geometry oriented, e.g. beam optical trading
    • B23K9/1276Using non-contact, electric or magnetic means, e.g. inductive means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00Arc welding or cutting
    • B23K9/02Seam welding; Backing means; Inserts
    • B23K9/028Seam welding; Backing means; Inserts for curved planar seams
    • B23K9/0282Seam welding; Backing means; Inserts for curved planar seams for welding tube sections
    • B23K9/0286Seam welding; Backing means; Inserts for curved planar seams for welding tube sections with an electrode moving around the fixed tube during the welding operation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00Articles made by soldering, welding or cutting
    • B23K2101/04Tubular or hollow articles
    • B23K2101/06Tubes

Description

Title Apparatus and method for welding pipes together Field of the Invention The present invention relates to an apparatus and method for welding pipes together. More specifically the invention relates to arc-welding together pipe sections when laying deep-sea pipelines underwater pipelines). The welding process used when laying such pipelines is commonly of the type where a continuous-wire arc welding torch is used.

When laying a pipeline at sea it is customary to weld, on a lay-barge, individual pipe sections to a pipe string (the pipe string leading towards the seabed). The welding process takes place close to the surface of the water.

The pipe sections may consist of a plurality of pipe lengths each welded together on the lay-barge to form the pipe sections when required.

15 The pipe-string, when being laid, is under great tension and weld joints must, of course, necessarily be sufficiently strong to withstand the high forces imposed on the weld joints. Each time a pipe is welded to another pipe extensive tests are made to ensure that the quality of the weld joint formed is sufficient. The strength of a weld joint depends upon various factors, one being the geometry of the path traced by the point of contact of the arc in relation to the surfaces of the pipes to be joined. If the point of contact of the arc is off target by as little as a tenth of a millimetre the quality of the joint may be reduced by enough that the pipe joint is rejected, when tested, as not being of sufficient quality. It is therefore important that the weld metal is laid down in the 25 region of the joint with great accuracy.

Furthermore the radial distance of the electrode with respect to the pipes must change in relation to the depth of the weld joint. As the region of the joint between the pipes is filled with welded metal the surface of the welded metal gets closer to the welding torch.

There are therefore special considerations that must be taken into account when designing an apparatus for welding such pipes together.

A known method of welding two pipes together may be described as follows. The pipes to be joined are prepared prior to the welding process by bevelling the ends of the pipes such that when the pipes are arranged immediately before the welding process commences (coaxially with respect to each other), an exterior circumferential groove is defined between the two pipes. The pipes are positioned ready for welding. A carriage is mounted on one of the pipes for movement around the circumference of the pipes to be joined. A welding torch is mounted on the carriage and the apparatus is so arranged that the end of the metal electrode of the torch is opposite and relatively close to the circumferential groove. The carriage is moved around the circumference of the pipe and the torch is operated so that an arc is directed into the groove. The arc is guided manually and/or by various mechanical sensors to guide the arc as accurately as possible along the length of the groove. The welding process generally takes several passes.

In the above-described method the resolution of the mechanical sensors is such that a human operator is required to assist in the welding process for guiding the arc with sufficient accuracy.

US 4,283,617 discloses an apparatus and method for automatically welding together pipe sections according to the preamble of claim 1. The 15 apparatus includes a torch transport assembly for moving two torches along the circumferential joint to be welded between the pipe sections. The two torches are separated by a distance equivalent to one quarter of the circumference of the pipe sections. Other welding apparatus/methods are described in US S. 4,485,291 and US 4,631,386.

The time it takes to lay a given length of pipeline is, to a great extent, determined by the time it takes to perform all the necessary welding operations.

There has therefore been a general desire to reduce the time it takes to weld two pipes together. Any attempt to speed up the welding process should not 44 however lead to a significant reduction in the quality of the weld joint.

25 An object of the present invention is to provide an apparatus and method *•*for welding pipes together that mitigates at least some of the above-mentioned disadvantages associated with the known method and apparatus described above. A further object of the present invention is to provide an apparatus and method for welding pipes together that is faster at welding pipes together than the known method and apparatus described above but without significantly reducing the quality of weld joint.

Thus the present invention provides a method of forming a pipeline including a step of welding two pipe together, said step of welding two pipes together comprising the steps of arranging two pipes end to end, the pipes being so shaped that a circumferentially extending groove is defined between the ends of the pipes, effecting relative movement of a plurality of arc welding torches arranged on a single carriage at substantially the same speed around the pipes, and operating said plurality of arc welding torches so that their arcs form a weld in the groove, characterised in that the pipeline formed is a deep sea pipeline, the angle of separation of the walls defining the groove between the pipes is less than 10 degrees, at least two torches of said plurality of arc welding torches are arranged directly adjacent to each other so that, during the operation of the torches, the arcs of said at least two torches are produced directly one after the other in the groove, and the arc produced by each of said plurality of arc welding torches is independently automatically electronically guided by ascertaining electrical o: 15 characteristics of the welding with regard to each pipe, respectively, and comparing the electrical characteristics relating to one of the pipes with the **-corresponding electrical characteristics relating to the other of the pipes.

Both the automation of the process and the provision of a plurality of .torches on the carriage facilitate the speeding of the welding process, whilst not necessarily significantly increasing the complexity or cost of the welding apparatus. Costs may also be reduced because there is no need for there to be a skilled operator for manually guiding the welding apparatus.

The automatic electronic guidance of the welding enables the method of the present invention to be used to weld pipes together, where the angle of separation of the walls defining the groove is less than 10 degrees. The angle of separation of the walls defining the groove is advantageously 6 degrees or less. Generally, the narrower the angle, the less weld material is required to .9 weld the pipes together satisfactorily. The walls defining the groove may even **be substantially parallel.

When the torches are first operated to form a weld, it is preferable for a first torch to start welding and for other torches to start welding only once they have reached the position at which the first torch was started. The torches may be shut down in order in a similar manner.

Many proposals have been made in the past to speed up the welding process with which the present invention is concerned. One such proposal is to provide more than one welding apparatus, each welding apparatus being operated by a respective welding operator. However, such a proposal requires the provision of separate carriages, which leads to an increase in costs. Also, because it has been customary in the past for the circumferential groove between the pipes to be tapered it has also been customary for the speed of the welding torch relative to the pipe to be slowed down as the depth of the weld joint increases, because as the depth increases the width of the layer of the weld joint to be formed increases and therefore the time required to form successive layers (of a given length along the groove) also increases. Thus proposals of providing two carriages each carrying a torch often require the carriages to be able to travel independently of each other and at different speeds, which causes complications in that efforts must be made to avoid the carriage and torch assemblies disrupting and interfering with each other.

The automation of the guiding of the welding torches according to the present invention facilitates the provision of a plurality of such torches mounted 15 on a single carriage. If the guiding of the torches were not fully automated, a *-**plurality of operators might be required in respect of a single carriage.

Furthermore the method of automatically guiding the torches according to the present invention does not require mechanical contact with the walls that define the groove and has been found to be highly accurate, which could lead to fewer welds being rejected, when subjected to the rigorous quality testing necessary when laying pipelines. Preferably, when the arcs are being moved along the length of the circumferential groove, the guidance of the arcs, insofar as the movement of the arcs in a direction along the axis of the pipe is controlled, is effected without any mechanical or optical sensors.

25 The axes of the torches may be substantially parallel. For example, the *o*axes of the torches may be arranged so that, in use, they each extend substantially radially with respect to the pipe.

**The guidance of the arcs can be, and preferably is, effected by a carriage moving circumferentially around the pipes and along the groove so that the torch points generally towards the groove and a control unit controls the exact position of the arcs by effecting correcting movements to the torch in a direction parallel to the axis of the pipe. Such correcting movements preferably, but not necessarily, move the arc to substantially the exact desired location.

As mentioned above, the arc produced by each of said plurality of arc welding torches is independently automatically electronically guided. Guiding each arc independently may facilitate the production of a higher quality weld joint. Preferably the process of automatically guiding the arcs includes a step of ascertaining the difference between a value representing an electrical characteristic relating to one pipe and a value representing the same electrical characteristic relating to the other pipe and then performing a correcting movement in which the position of the arc is moved in dependence on the value of the difference. For example, the position of the arc may be moved a preset distance (for example, in a direction along the axis of the pipe) if the value of the difference is outside a predetermined range of acceptable values.

The direction of the movement may depend on whether the value of the difference is above a high threshold value or below a low threshold value. The magnitude of the correcting movement could depend on the value of the difference.

The measurements, from which the values of the electrical 15 characteristics compared are ascertained, are of course preferably taken with °*°the arc being at substantially the same distance along the length of the groove.

S* If a correcting movement is only effected when the value of the difference falls outside an acceptable range of values it is preferable to have a further means of correcting the movement. If over time the value of the difference is indicative of the arc being continuously off position to one side of the desired path, but not by enough to cause the value of the differenceto be outside the predetermined acceptable range, then it is nonetheless desirable to correct that small, but persistent discrepancy in the position of the arc. The method therefore preferably further comprises monitoring the values of the 25 differences over time and if the values of the differences are indicative of the *o*arc being substantially continuously to one side of the desired path a correcting movement of the arc is effected. For example an integrating device might be provided to calculate a running sum of the values of the calculated differences.

The electrical characteristics that are ascertained may include one or more of voltage, potential difference, current, current intensity and arc impedance. The characteristics are preferably ascertained by measuring electrical characteristics of the arcs of the welding torches.

The torches need not all be operated in the same manner. Some torches may be operated at different currents for example. Two of the torches effecting welding of the pipe, may weld at different rates. For example, one torch may be fed with welding wire at a different rate.

Preferably, there are two welding torches mounted on the carriage.

Preferably each torch is a continuous wire arc welding torch. For example, in use, the wire is fed into the torch and, by means of the arc welding process, fills the groove between the pipes to form the weld joint. The supply of the wire is advantageously mounted remotely from the carriage. Having the supply of wire being remotely provided makes the carriage lighter and consequently easier to operate. The wire may be mounted on a spool. A typical spool of wire can weigh about Preferably, each torch is movable independently in a direction having a component parallel to the axis of the pipe.

A suitable method of ascertaining the necessary values of the electrical characteristics relating to each respective pipe is described below. A step of that method preferably includes oscillating each welding torch so that the position of each arc alternatively moves from one side to the other of the 15 general path being traced along the groove by each respective torch. The :'***torches are thus preferably moved so that the respective positions of the arcs within the groove oscillate between the walls defining the groove. Each welding torch is preferably oscillated so that the position of each arc altemrnatively moves generally towards and away from the walls of the groove. The oscillatory movement of each arc is preferably in a direction having a component in a direction along the axis of the pipe. Preferably, the direction of the oscillatory movement is substantially perpendicular to the length of the groove. Preferably, the direction of the oscillatory movement is substantially parallel to the axis of :the pipe. The oscillatory movement of the arcs towards and away from the 25 walls of the groove is advantageously small in comparison to the width of the weld layer being deposited at a given time. The amplitude of the oscillatory oooo movement is advantageously so small that the quality of the weld being formed **is not significantly affected. For example, the amplitude of the oscillations of the arc may, during at least some stage in the welding process, be less than a tenth of a millimetre.

As indicated above, the step of ascertaining the electrical characteristics of the welding with regard to each pipe preferably includes a step of oscillating the position of the arcs in the groove. Since the electrical characteristics of an arc change in dependence upon the relative position of the arc in the groove, an indication of the position of the arc within the groove can be ascertained, by observing and comparing the electrical characteristics of the arc, as the distance of the arc from the walls changes.

The movement of each torch in said direction having a component parallel to the axis of the pipe is preferably driven by a respective independent prime mover. A single prime mover preferably effects motion of the torches along the length of the groove. The or each prime mover may be an electric motor, preferably a brushless electric motor.

Advantageously, each torch is cooled during operation. In that case, each torch may be provided with means for cooling the torch during operation.

When a torch is operated in close proximity to another torch that is also being operated the excessive amount of heat generated by the two torches can cause mechanical problems to the torches or other apparatus in the vicinity, if the heat is not properly dissipated. Preferably the torches are each water cooled. Preferably the water cooling system of a torch effects cooling of the 15 welding tip of that torch.

The invention also provides a method as described above, wherein the S. pipes are of a size and have a wall thickness suitable for forming a deep sea pipeline, and the pipes are joined by butt welding effected by an automatically guiding welding apparatus, the method comprising the steps of arranging coaxially two pipes to be joined next to each other, the end walls of the pipes facing each other defining a circumferentially extending bevelled groove having a left wall and a right wall, providing a welding apparatus including a guide mounted around the circumference of the pipe, S 25 at least one automatic tracking trolley mounted on the guide for movement therealong and around the pipe under the control of a control unit, the or each trolley comprising locking and sliding devices engageable with the guide, and pulling units for pulling the or each trolley along the guide, two continuous-wire oscillating welding torches mounted on the or each trolley, and a wire feeding means for feeding wire to each oscillating welding torch, moving the welding torches around the guide and operating the torches to effect welding of the left wall and right wall of the groove to weld the pipes together, iu~r ;n;un i~ii ~r i, rui lliYLIi_ in respect of each torch, ascertaining, at each of a multiplicity of instants over time, electrical parameter values relating to the voltage, current intensity and voltaic arc impedance of both the left wall and the right wall of the groove during the continuous movement of the oscillating torches, in respect of each torch, calculating the difference between the electrical parameter values for the right wall and for the left wall, in respect of each torch, comparing the values of the differences calculated, at each instant, with preset values held in a processing means to determine, at each instant, the shifting of those values, piloting the variation in the movements of each oscillating welding torch by activating, each time the shifting in relation to the respective torch exceeds a preset limit, a drive means for orienting the torch so that the welding run is deposited in the centre of the throat of the groove and then substantially superimposing the welding run on the notional central line of the groove, and 15 providing a protective atmosphere of active carbon dioxide gas, whereby •pipes with walls that are relatively thick and so bevelled that the angle between the left and right walls of the groove defined between the ends of the pipes is relatively low may be quickly welded together in an economical manner.

The present invention also provides a method of constructing an underwater pipeline including using the method according to the present invention as described herein. The technique used in laying the underwater pipeline may be the J-lay method.

If the above-described invention is used to connect a pipe section to a pipeline one of the two pipes will be the pipe section and the other will of course be the free end of the pipeline to which the pipe section is to be *connected. Whilst in the case where a pipe section is to be welded to a S* pipeline it is necessary for the pipe section to be prevented from rotating, at least some of the features of the present invention can, of course, also be of use when welding pipes together, such as for example when welding pipe lengths together to form a pipe section, where it is possible for the pipes to rotate and for the welding apparatus to remain stationary.

According to the invention there is also provided a welding apparatus for use in the method of the above-described invention, the apparatus comprising a carriage carrying a plurality of arc welding torches, 1- -11-1 1- 1" lr a control unit for facilitating automatic guidance of the arcs produced by the torches, wherein the apparatus is so configured that it may be Used to weld together two pipes laid end to end defining therebetween a groove, by arranging the apparatus so that the carriage is mounted for movement around the circumference, *of the pipes, the control unit receives signals representing electrical characteristics of the welding with regard to each pipe, respectively, whereby the. control unit facilitates independent automatic guidance of the arc of.

each torch along the groove by comparing the signals relating to. one of the pipes with the corresponding signals relating to the other of the pipes. Each torch is preferably provided with a respective control unit. Further examples of how the apparatus may be configured to perform an aspect of the method of the present invention include each welding torch preferably being so arranged 15 that it is able in use to effect an oscillatory movement of the arc and each welding torch preferably being able to be oscillated so that, in use, the position of each arc alternatively moves generally towards and away from the walls of :the groove.

*.:Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings of which: Fig 1. is a schematic side view of a welding apparatus including two welding torches (only one of which is shown for the purpose of clarity) according to a first embodiment of the present invention; Fig 2. is a schematic block diagram illustrating the automatic guidance .25 system of the welding apparatus of the first embodiment; and Fig 3. is a schematic perspective view of a welding apparatus including two welding torches according to a second embodiment of the present invention.

Figure 1 shows in partial cross-section the ends of the pipes 2, 4 to be welded together and a schematic side view of a welding apparatus 10 having two voltaic arc-welding torches 1 (only one of which can be seen in Figure 1) for butt welding the pipes 2, 4 together. The welding torch is of the well known GMAW (gas metal arc welding) and can either be of the type used in MAO (metal active gas) welding or of the type used in MIG (metal inert gas) Welding.

The gas used may for example be carbon dioxide.

The pipes 2, 4 are arranged with their axes aligned and their ends 26, 27 next to each other. The ends 26, 27 of the pipes are bevelled so that when brought together they define a circumferentially extending exterior groove 28.

A track 6 is fixedly mounted as a single unit on the left hand pipe 2 (as viewed in Figure The track 6 extends circumferentially around the pipe 2.

The track 6 has two guide tracks 29, 30 that extend around the pipe 2. The welding apparatus 10 is mounted for movement along the track 6. Wheels 5 are rotatably mounted on a base plate 7 of the welding apparatus 10. The wheels engage with the guide tracks 29, 30 and facilitate the guided movement of the apparatus 10 along the track 6. One of the tracks 30 also provides a toothed rack that extends around the pipe. A pinion wheel (not shown), mounted for engagement with the rack, is driven so that the apparatus may be driven around the pipe 2. The driven pinion wheel may be rotated via a driven chain, which is in turn driven by a stepper motor, or similar driving source (not S 15 illustrated). The track 6 is so positioned on the pipe 2 that the torches 1 of the apparatus 10 are each positioned directly over the groove 28. Such methods of positioning a track and a welding apparatus on a pipe so that a torch of the ,:welding apparatus is correctly positioned over the weld joint to be formed are S. well known and are therefore not described here in further detail.

In use, the apparatus 10 is driven around the pipes 2, 4 and the welding torches 1 are operated and controlled so that they deposit weld material in the centre of the groove 28 to form a weld joint 3. The weld torches are arranged next to each other. When the apparatus is started up the first torch (the torch at the front in respect of the initial direction of motion of the torches) is operated 25 first and the other torch is not operated until it reaches the start of theweld laid down by the first torch. Then, as the apparatus 10 passes along the groove 28, weld material is deposited in the groove by the first torch to form the weld joint and shortly thereafter further weld material is deposited on top of the weld .I joint 3 by the second torch. The apparatus 10 performs several passes depositing further layers of weld material in the groove to join the pipes together. The welding apparatus 10 rotates in both directions around the circumference of the pipes 2, 4. The welding apparatus 10 moves around the pipes 2, 4 in one direction clockwise or anticlockwise) until it has moved around the entire circumference of the pipes at least once.

~.~;-r~~ri--Y;l~iii~~ilri~ryi;liii~i i~i i iiii~i~ii~^ YI ii iii~ii.i"ll*l~Ylli~LI ii~-i~:ilYO ~i*-irC-ilihii~i~ili n iir ruiif-il~r~r I~I-~L.CIII~-; I li-i.~~X-i-r^irT~ ~i*il~i*-7f~ir" i~-~illi* iu*iYiil 11 Both torches 1 function in a similar way. The following description relates to only one of the two torches and its guidance system, but it will be understood that the other torch functions in substantially the same way.

Welding wire 9 is continuously fed from a spool 11 of wire to the torch 1.

The welding wire 9 is unwound from the wire spool 11 by means of a pulling device 14 which conveys the wire 9 via a guiding pipe 8 to a straining device 12, from where the wire is fed into the torch 1.

The welding of the pipes 2 and 4, by the welding torch is controlled by an automatic guidance system. The guidance system guides the welding:torch by ascertaining electrical parameter values relating to the voltaic arc impedance.

The arc impedance depends on, inter alia, the position of the welding arc in relation to the walls defining the groove 28. If the arc lies in the notional central plane (containing the centre line of the groove 28) halfway between the walls of the groove 28, then the influence of those walls on the above electrical parame- 15 ters is practically identical. On the other hand, if the arc of the voltaic torch 1 is not positioned directly in the centre of the groove 28 the influence of the walls of the groove on the electrical parameter values will be different. Monitoring the magnitudes of an electrical parameter ascertained enables the control unit (not shown in Figure 1) of the apparatus to calculate the deviation from the central position of the arc of the torch 1 in the groove 28. More specifically the magnitude of the values of voltage, current and impedance I, R) relating to one wall of the groove 28 are compared with those relating to the other wall of the groove, during the continuous movement of the torch 1. The voltage and current of the arc is measured with equipment attached to or in the welding torch and the arc impedance can then be calculated using those measured values. The method of ascertaining those values in respect of a given wall of o ~the groove 28 is explained below with reference to Figure 2.

S' If the arc is in an off-centre position, in that the arc, the end of the wire 9 and welding bath are closer to one of the walls of the groove there will be a decrease in the voltaic arc impedance with respect to the opposite wall, since the welding apparatus is such that the voltage value is caused to decrease and the current intensity is caused to increase. Corrections in the orientation and position of the torch 1 in relation to the groove 28 and the weld 3 are achieved with the automatic guidance system in real time.

The block diagram of Figure 2 illustrates schematically the automatic guidance system of the welding apparatus according to the first embodiment (illustrated by Figure 1) of the present invention. Each torch is provided with a guidance system, but the system is illustrated and described with reference to a single torch only for the sake of simplicity.

The guidance system periodically ascertains the electrical parameter values of voltage, current intensity and voltaic arc impedance relating to the right wall and left wall which define the groove 28 (see Figure The welding torch is oscillated so that the position of the arc oscillates with a small amplitude in a direction substantially parallel to the axis of the pipe (so that the arc moves towards and away from each wall). The arc voltage and current are measured practically continuously and signals corresponding to those measured values are passed from the torch 1 via a cable 25 to a governing unit The governing unit 15 includes a processing means, which processes the signals. The governing unit 15 sends signals representative of the electrical parameter values measured for the left and right walls to two digital filters 16, 15 18, one filter 16 for generating signals relating to the right wall and one filter 18 for the left wall. The governing unit 15 and filters 16, 18 are thus able *..effectively to extract, from the signals from the torch 1, signals corresponding to S: values of the parameters measured in respect of the arc in relation to the left wall and right wall, respectively, of the groove 28. Output signals are thus produced by the filters 16, 18 relating to the voltage, current and impedance values relating to their respective wall of the groove.

A difference unit 19 calculates an indication of the position in the groove of the arc of the torch by calculating the differences in the values relating to the left and right walls respectively, determined from the signals received from the S 25 filters 16, 18. The calculations, which are made practically continuously, are used in real time for controlling the position and orientation of the torch 1 in S° relation to the groove 28.

If the calculations made, indicate that the difference in desired position of the arc and the actual position of the arc is greater than a fixed and preset threshold distance, then a signal is generated which causes a gain unit 21 to activate a command signal, which by means of an amplifier 22, causes a drive unit 23 in association with a centring regulation unit 24 to move the welding torch 1, so that the arc is moved towards the desired location (the centre line of the groove).

If the calculations made (by the difference unit 19) indicate that the difference in desired position of the arc and the actual position of the arc .is less 13 than or equal to the preset threshold distance, the gain unit 21 does not cause the torch to be moved. However signals representing the difference values calculated by the difference unit 19 are sent to an integrator unit 20 that is also provided to regulate the positioning of the torch 1 during the welding process.

If the position of the arc remains near the central line of the groove 28, and the sum of the distances to the left of the line is practically equal, over time, to the sum of the distances to the right of the line the integrator 20 will not generate any centring movement command signal through the amplifier 22. However, if the position of the arc, although remaining within the tolerated range of distances from the central line of the groove, is found to be prevalently to one side of the line, then the integrator 20 activates a command signal, which by means of the amplifier 22, causes the drive unit 23 and centring regulation unit 24 to move the welding torch 1, so that the arc is moved towards the desired location (the centre line of the groove).

15 The calculations performed by the automatic guidance system may include performing comparisons between calculated values relating to the actual state of the welding system and sample values held in the memory of the guidance system. Such sample values may be entered into the memory manually by keyboard.

Figure 3 shows schematically a welding apparatus 110 according to a second embodiment of the present invention in perspective view. The apparatus operates in a similar manner to that of the first embodiment described above. The welding torches 101 are aligned so that when the apparatus 110 is mounted on a pipe (not shown in Fig.3) they both point S* 25 towards the same notional circumferential line extending around the pipe.

Wheels 105 are provided for engaging with a guide track (not shown in Fig.3) that, in use, extends around one of the pipes to be welded.

The main differences between the apparatus according to the second embodiment and that of the first embodiment will now be described.

The welding wire (not shown) of the second embodiment is not provided on the movable welding apparatus 110, rather it is mounted at a location remote from the apparatus, and fed from that remote location, via a guide pipe, to the welding apparatus as it moves around the pipe. It is therefore useful that the apparatus is able to move both clockwise and anticlockwise around the pipe, to reduce the chance of the welding wire becoming twisted.

14 The torches 101 are each water cooled. The water is pumped around a cooling system (not shown) including parts of the torch. The water heated by the operating torch passes into a heat exchanger, such as a radiator, so that it is cooled.

o* o• o n;*UI;U~IY iiiri\iiIni Vlv*Uh'i*r~

Claims (22)

1. A method of forming a pipeline including a step of welding two pipes together, said step of welding two pipes together comprising the steps of arranging two pipes end to end, the pipes being so shaped that a circumferentially extending groove is defined between the ends of the pipes, effecting relative movement of a plurality of arc welding torches arranged on a single carriage at substantially the same speed around the pipes, and operating said plurality of arc welding torches so that their arcs form a weld in the groove, characterised in that the pipeline formed is a deep sea pipeline, the angle of separation of the walls defining the groove between the pipes is less than 10 degrees, at least two torches of said plurality of arc welding torches are arranged S 15 directly adjacent to each other so that, during the operation of the torches, the arcs of said at least two torches are produced directly one after the other in the :groove, and :the arc produced by each of said plurality of arc welding torches is independently automatically electronically guided by ascertaining electrical characteristics of the welding with regard to each pipe, respectively, and comparing the electrical characteristics relating to one of the pipes with the corresponding electrical characteristics relating to the other of the pipes.
2. A method according to claim 1, wherein the axes of said at least two i torches arranged directly adjacent to each other are substantially parallel. 6 25
3. A method according to claim 1 or claim 2, wherein said plurality of arc welding torches are GMAW (gas metal arc welding) torches.
4. A method according to any preceding claim, wherein said plurality of arc welding torches are operated using a MAG (metal active gas) welding process.
5. A method according to any preceding claim, including the step of ascertaining the difference between a value representing an electrical characteristic relating to one pipe and a value representing the same electrical characteristic relating to the other pipe and then performing a correcting movement moving the position of the arc in dependence on the value of the difference. "n~~ri"CI ~.*i(*UU~i(l(lnlit~iri:liUilTn~ililil~W UIMIYI*ICh~N~ll~nII-ilU7YIYl~iiill~h\ PIUI~IIT IIIJ**IUh Eirij*i~~illjilUIU11~* *hU'11 cVlr~r.~iillig 'iliiiiY~U* hirv~;r*r~Pl"h~ii"C""~*:ui 16
6. A method according to claim 5, wherein a correcting movement is effected when the value of the difference falls outside an preset acceptable range of values.
7. A method according to claim 6, further comprising monitoring the values of the differences over time and if the values of the differences is indicative of the arc being substantially continuously to one side of the desired path effecting a correcting movement of the arc.
8. A method according to any preceding claim, wherein the electrical characteristics that are ascertained include one or more of the arc voltage, the current, and the arc impedance.
9. A method according to any preceding claim, wherein two of the torches effecting welding of the pipe, weld at different rates.
A method according to any preceding claim, wherein each torch is a continuous wire arc welding torch and the supply of the wire is mounted 15 remotely from the carriage.
11. A method according to any preceding claim, wherein the angle of separation of the walls defining the groove is 6 degrees or less.
12. A method according to any preceding claim, wherein the walls defining the groove are substantially parallel.
13. A method according to any preceding claim, wherein each torch is movable independently in a direction having a component parallel to the axis of the pipe.
14. A method according to any preceding claim, wherein the torches are moved so that the respective positions of the arcs within the groove oscillate 2* 25 between the walls in a direction having a component parallel to the axis of the pipe.
15. A method according to any preceding claim, wherein the movement of each torch in said direction having a component parallel to the axis of the pipe is driven by a respective independent prime mover.
16. A method according to any preceding claim, wherein a single prime mover effects motion of the torches along the length of the groove.
17. A method according to any preceding claim, wherein each torch is cooled during operation.
18. A method according to claim 17, wherein the torches are water cooled.
19. A method according to any preceding claim, wherein the pipes are of a size and have a wall thickness suitable for forming a deep sea pipeline, and the pipes are joined by butt welding effected by an automatically guiding welding apparatus, the method comprising the steps of arranging coaxially two pipes to be joined next to each other, the end walls of the pipes facing each other defining a circumferentially extending bevelled groove having a left wall and a right wall, providing a welding apparatus including a guide mounted around the circumference of the pipe, at least one automatic tracking trolley mounted on the guide for movement therealong and around the pipe under the control of a control unit, the or each trolley comprising locking and sliding devices engageable with the guide, and pulling units for pulling the or each trolley along the guide, two continuous-wire oscillating welding torches mounted on the or each trolley, and a wire feeding means for feeding wire to each oscillating welding 15 torch, moving the welding torches around the guide and operating the torches to effect welding of the left wall and right wall of the groove to weld the pipes together, in respect of each torch, ascertaining, at each of a multiplicity of instants over time, electrical parameter values relating to the voltage, current intensity and voltaic arc impedance of both the left wall and the right wall of the groove during the continuous movement of the oscillating torches, in respect of each torch, calculating the difference between the electrical parameter values for the right wall and for the left wall, 25 in respect of each torch, comparing the values of the differences calculated, at each instant, with preset values held in a processing means to determine, at each instant, the shifting of those values, piloting the variation in the movements of each oscillating welding torch by activating, each time the shifting in relation to the respective torch exceeds a preset limit, a drive means for orienting the torch so that the welding run is deposited in the centre of the throat of the groove and then substantially superimposing the welding run on the notional central line of the groove, and providing a protective atmosphere of active carbon dioxide gas, whereby pipes with walls that are relatively thick and so bevelled that the angle between the left and right walls of the groove defined between the ends of the 11,111.1 ,11 1,1 "1.11 i 1.1- ll- l I.R.1k" l- 18 pipes is relatively low may be quickly welded together in an economical manner.
Welding apparatus for use in a method as claimed in any of the preceding claims, the apparatus comprising a carriage carrying a plurality of arc welding torches which are arranged directly adjacent to each other, and a control unit for facilitating automatic guidance of the arcs produced by the torches, wherein the apparatus is so configured that it may be used to weld together two pipes laid end to end defining therebetween a groove, the walls defining the groove being separated by an angle of less than 10 degrees, the carriage being mountable for movement around the circumference of the pipes, the arcs of at least two torches being produced, in use directly one after the other in the groove, 15 the control unit being configured to receive, in use, signals representing electrical characteristics of the welding with regard to each pipe, respectively, whereby the control unit facilitates independent automatic guidance of the arc of each torch along the groove by comparing the signals relating to one of the pipes with the corresponding signals relating to the other of the pipes.
21. Apparatus according to claim 20, wherein each torch is provided with a respective control unit. DATED THIS
22 DAY OF JANUARY 2003 Saipem S.p.A. Patent Attorneys for the Applicant: F B RICE CO
AU22872/00A 1998-12-24 1999-12-21 Apparatus and method for welding pipes together Expired AU769692B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB9828727 1998-12-24
GBGB9828727.9A GB9828727D0 (en) 1998-12-24 1998-12-24 Apparatus and method for welding pipes together
PCT/EP1999/010505 WO2000038872A1 (en) 1998-12-24 1999-12-21 Apparatus and method for welding pipes together

Publications (2)

Publication Number Publication Date
AU2287200A AU2287200A (en) 2000-07-31
AU769692B2 true AU769692B2 (en) 2004-01-29

Family

ID=10845093

Family Applications (1)

Application Number Title Priority Date Filing Date
AU22872/00A Expired AU769692B2 (en) 1998-12-24 1999-12-21 Apparatus and method for welding pipes together

Country Status (15)

Country Link
US (1) US6429405B2 (en)
EP (1) EP1077785B2 (en)
AT (1) AT219406T (en)
AU (1) AU769692B2 (en)
BR (1) BR9916568A (en)
CA (1) CA2355625C (en)
DE (1) DE69901900T3 (en)
DK (1) DK1077785T4 (en)
ES (1) ES2178500T5 (en)
GB (1) GB9828727D0 (en)
NO (1) NO322350B1 (en)
NZ (1) NZ512090A (en)
PT (1) PT1077785E (en)
TR (1) TR200101816T2 (en)
WO (1) WO2000038872A1 (en)

Families Citing this family (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6270140B1 (en) * 1997-07-16 2001-08-07 Johnson Controls Technology Corporation Removable seat
GB9904422D0 (en) * 1998-07-22 1999-04-21 Saipem Spa Improvements in and relating to underwater pipe-laying
NL1011223C2 (en) 1999-02-05 2000-08-10 Allseas Group Sa Method and device for welding two pipes together.
CA2379124A1 (en) 1999-07-21 2001-02-01 Teresio Signaroldi Improvements in and relating to underwater pipe-laying
AU2363502A (en) 2000-10-24 2002-05-06 Saipem Spa Method and apparatus for welding pipes together
GB2373750A (en) 2001-03-27 2002-10-02 Saipem Spa Welding pipe-in-pipe pipelines
BR0117112A (en) * 2001-08-21 2004-08-17 Serimer Dasa Real-time welding arc penetration detection system
KR100617766B1 (en) * 2002-09-02 2006-08-28 현대중공업 주식회사 Pipe orbital welding carriage
US8680432B2 (en) * 2005-04-20 2014-03-25 Illinois Tool Works Inc. Cooperative welding system
KR100982106B1 (en) 2005-06-29 2010-09-13 현대중공업 주식회사 Sub sea pipe line automatic welding carriage having the handle combination clamping device
JP4891726B2 (en) * 2006-10-06 2012-03-07 株式会社神戸製鋼所 Robot controller for controlling tandem arc welding system and arc scanning control method using the same
GB0621780D0 (en) 2006-11-01 2006-12-13 Saipem Spa Welding system
US20080302539A1 (en) * 2007-06-11 2008-12-11 Frank's International, Inc. Method and apparatus for lengthening a pipe string and installing a pipe string in a borehole
CA2706955A1 (en) * 2007-11-28 2009-06-04 Frank's International, Inc. Methods and apparatus for forming tubular strings
GB0801917D0 (en) 2008-02-01 2008-03-12 Saipem Spa Method and apparatus for the welding of pipes
EP2314406A4 (en) * 2009-02-25 2015-04-22 Panasonic Ip Man Co Ltd Welding method and welding system
DE102009020146B3 (en) * 2009-04-08 2010-06-10 V & M Deutschland Gmbh Connecting ends of steel tubes by orbital welding in laser-light-arc hybrid technology, comprises connecting tube ends with welding positions, and guiding laser- and light arc welding head as tool over guiding ring during welding process
DE102009058051B4 (en) * 2009-12-14 2011-11-10 Osman Algün Manually powered welding apparatus for arc welding and arc welding method
JP5450150B2 (en) * 2010-02-18 2014-03-26 株式会社神戸製鋼所 Control method of tip-base metal distance by arc welding system and arc welding system
AT509762B1 (en) * 2010-04-27 2012-03-15 Dtec Gmbh Method and device for producing a panel with a welded tube
US8987637B1 (en) * 2010-10-21 2015-03-24 The Reliable Automatic Sprinkler Co, Inc. Welding torch oscillator with motorized pitch control
US9969025B2 (en) 2011-11-18 2018-05-15 Lincoln Global, Inc. System for mounting a tractor unit on a guide track
CN104379292A (en) * 2011-11-24 2015-02-25 焊接机器人公司 System and method for modular portable welding and seam tracking
US9527153B2 (en) 2013-03-14 2016-12-27 Lincoln Global, Inc. Camera and wire feed solution for orbital welder system
US10480862B2 (en) 2013-05-23 2019-11-19 Crc-Evans Pipeline International, Inc. Systems and methods for use in welding pipe segments of a pipeline
US10589371B2 (en) * 2013-05-23 2020-03-17 Crc-Evans Pipeline International, Inc. Rotating welding system and methods
US10695876B2 (en) 2013-05-23 2020-06-30 Crc-Evans Pipeline International, Inc. Self-powered welding systems and methods
US9770775B2 (en) 2013-11-11 2017-09-26 Lincoln Global, Inc. Orbital welding torch systems and methods with lead/lag angle stop
US9517524B2 (en) 2013-11-12 2016-12-13 Lincoln Global, Inc. Welding wire spool support
US9731385B2 (en) 2013-11-12 2017-08-15 Lincoln Global, Inc. Orbital welder with wire height adjustment assembly
WO2016033568A1 (en) 2014-08-29 2016-03-03 Crc-Evans Pipeline International Inc. Method and system for welding
CN104400181B (en) * 2014-12-02 2016-06-29 哈尔滨工业大学(威海) Mariages underwater wet welding device and method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4283617A (en) * 1976-02-03 1981-08-11 Merrick Welding International, Inc. Automatic pipe welding system
US4485291A (en) * 1982-04-26 1984-11-27 Nippon Kokan Kabushiki Kaisha Method for controlling the position of welding electrode in arc-welding with weaving
US4631386A (en) * 1984-05-14 1986-12-23 Slavens Clyde M Welding head apparatus

Family Cites Families (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3800116A (en) 1970-12-29 1974-03-26 Sumitomo Metal Ind Apparatus for automatically welding pipe joints for cylindrical members such as steel pipe piles
US3777115A (en) 1972-02-22 1973-12-04 Astro Arc Co Apparatus for controlling electrode oscillation
US3974356A (en) * 1974-08-26 1976-08-10 Crc-Crose International, Inc. Multiple arc welding device and method
US4350868A (en) 1975-07-14 1982-09-21 Matsushita Electric Industrial Co., Ltd. Follow-up control apparatus for controlling the movement of a welding weaving device
US4145593A (en) 1976-02-03 1979-03-20 Merrick Welding International, Inc. Automatic pipe welding system
US4380695A (en) 1976-07-06 1983-04-19 Crutcher Resources Corporation Control of torch position and travel in automatic welding
US4151395A (en) 1976-07-06 1979-04-24 CRC-Crose, International, Inc. Method and apparatus for electric arc and analogous welding under precision control
US4373125A (en) 1977-07-22 1983-02-08 Astro-Arc Company Apparatus for welding pipes
US4336440A (en) 1979-07-03 1982-06-22 Westinghouse Electric Corp. Weld tracking/electronic arc sensing system
JPS644875B2 (en) 1980-11-28 1989-01-27 Nippon Kokan Kk
JPS6311104B2 (en) 1981-09-24 1988-03-11 Kobe Steel Ltd
US4495400A (en) 1982-04-26 1985-01-22 Crutcher Resources Corporation Method and apparatus for positioning a welding torch in automatic electric welding
JPS59191575A (en) 1983-04-13 1984-10-30 Mitsubishi Electric Corp Tracing device for weld line
US4525616A (en) 1984-01-03 1985-06-25 Evans Pipeline Equipment Company Internal pipe welding apparatus
JPS62118976A (en) 1985-11-18 1987-05-30 Nippon Steel Corp Groove seam profiling method
US4990743A (en) 1989-05-10 1991-02-05 Daihen Corporation Control method for tracing a weld line in a welding apparatus
US5030812A (en) 1989-06-13 1991-07-09 Nkk Corporation Method for one-side root pass welding of a pipe joint
FR2656555B1 (en) 1989-12-29 1994-10-28 Serimer Mechanical system for automatic guidance of one or more torches of an arc welding unit.
US5059765A (en) 1990-01-04 1991-10-22 Crc-Evans Pipeline International, Inc. Method of operation for high speed automatic welding
NL9002398A (en) * 1990-11-02 1992-06-01 Atlantic Point Inc Device for welding pipes.
US5347101A (en) 1994-02-07 1994-09-13 Mcdermott International, Inc. Automatic tracking system for pipeline welding
US5593605A (en) 1994-10-11 1997-01-14 Crc-Evans Pipeline International, Inc. Internal laser welder for pipeline
US5796069A (en) 1997-01-10 1998-08-18 Crc-Evans Pipeline International, Inc. Arc and laser welding process for pipeline
IT1292205B1 (en) 1997-06-26 1999-01-25 Saipem Spa automatic tracking process of the joint bevel for the butt welding of pipes and apparatus for carrying out
GB2345016B (en) 1998-12-24 2003-04-02 Saipem Spa Method and apparatus for welding pipes together

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4283617A (en) * 1976-02-03 1981-08-11 Merrick Welding International, Inc. Automatic pipe welding system
US4485291A (en) * 1982-04-26 1984-11-27 Nippon Kokan Kabushiki Kaisha Method for controlling the position of welding electrode in arc-welding with weaving
US4631386A (en) * 1984-05-14 1986-12-23 Slavens Clyde M Welding head apparatus

Also Published As

Publication number Publication date
CA2355625C (en) 2009-02-03
AT219406T (en) 2002-07-15
NO20013170D0 (en) 2001-06-22
BR9916568A (en) 2001-10-02
NO322350B1 (en) 2006-09-18
EP1077785B2 (en) 2007-10-17
DE69901900T3 (en) 2008-02-28
EP1077785B1 (en) 2002-06-19
EP1077785A1 (en) 2001-02-28
US6429405B2 (en) 2002-08-06
TR200101816T2 (en) 2001-11-21
DK1077785T4 (en) 2007-11-26
DK1077785T3 (en) 2002-10-14
WO2000038872A1 (en) 2000-07-06
NZ512090A (en) 2002-12-20
AU2287200A (en) 2000-07-31
NO20013170L (en) 2001-08-21
GB9828727D0 (en) 1999-02-17
PT1077785E (en) 2002-10-31
DE69901900D1 (en) 2002-07-25
ES2178500T3 (en) 2002-12-16
US20010015349A1 (en) 2001-08-23
CA2355625A1 (en) 2000-07-06
DE69901900T2 (en) 2003-01-09
ES2178500T5 (en) 2008-03-01

Similar Documents

Publication Publication Date Title
AU2014268528B2 (en) Laser controlled internal welding machine for pipelines
EP2691204B1 (en) Welding electrode stickout monitoring and control
US9539662B2 (en) Extraction of arc length from voltage and current feedback
JP3464439B2 (en) Electric welding apparatus and method
US7498542B2 (en) Control method and system for a trackless autonomous crawling all-position arc welding robot with wheels and permanent magnet caterpillar belts
US10480862B2 (en) Systems and methods for use in welding pipe segments of a pipeline
CN100522453C (en) Orbital welding device for pipeline construction
KR102198122B1 (en) Synchronized rotating arc welding method and system
DK178480B1 (en) Method and apparatus for placing ends of pipe sections relative to each other
CA2299569C (en) Method and apparatus for electric arc welding
CN104010756B (en) welding wire feeding system and device
US4380695A (en) Control of torch position and travel in automatic welding
US4782206A (en) Method and apparatus for controlling weld bead shape to eliminate microfissure defects when shape melting austenitic materials
US6649870B1 (en) System and method facilitating fillet weld performance
US6744012B2 (en) Control method of arc welding and arc welder
US8592719B2 (en) System and method for identifying welding consumable wear
JP4891726B2 (en) Robot controller for controlling tandem arc welding system and arc scanning control method using the same
US5227601A (en) Adjustable welding torch mounting
EP0111110B1 (en) Automatic weld line following method
US20030038156A1 (en) Method for continuously regulating or tracking a position of a welding torch or a welding head
EP2782701B1 (en) System and method for modular portable welding and seam tracking
US20180031152A1 (en) Internally welded pipes
US4144992A (en) Method for controlling an automatic pipe welder
KR20080001821A (en) Plasma automatic welding machine for pipe circle welding
US5981906A (en) Method of welding the ends of pipe together using dual welding wires

Legal Events

Date Code Title Description
MK6 Application lapsed section 142(2)(f)/reg. 8.3(3) - pct applic. not entering national phase
TH Corrigenda

Free format text: IN VOL 14, NO 40, PAGE(S) 7168-7171 UNDER THE HEADING APPLICATIONS LAPSED, REFUSED OR WITHDRAWN PLEASE DELETE ALL REFERENCE TO APPLICATION NO. 22688/00 AND 22872/00

FGA Letters patent sealed or granted (standard patent)
MK14 Patent ceased section 143(a) (annual fees not paid) or expired